In general, a refrigerator is a device for freshly keeping storage items such as food and beverage, in fresh storage for a long period of time, and refrigerating or freezing storage items according to their types desired to be kept in storage.
The refrigerator operates according to driving of a compressor provided therein. Cooling air provided to the inside of the refrigerator is generated according to a heat exchange operation of a refrigerant and continuously provided to the inside of the refrigerator according to a repeated cycling operation of compression-condensation-expansion-evaporation. The refrigerant provided to the inside of the refrigerator is evenly transferred to the inside of the refrigerator by a convection current so that the food items within the refrigerator can be kept at a desired temperature.
Meanwhile, a refrigerator, air conditioner, etc. is provided with a compressor, and generally uses a brushless direct current (BLDC) compressor or reciprocating compressor.
The reciprocating compressor is a compressor that sucks, compresses and exhausts refrigerant gas through linear reciprocating motions of a piston provided inside a cylinder. The reciprocating compressor can be divided into a recipro type and a linear type according to the method of driving a piston.
The recipro type is such a type that changes rotary motions of a rotary motor into linear reciprocating motions by coupling a crankshaft to the motor and coupling a piston to the crankshaft. On the other hand, the linear type is such a type that reciprocates a piston through linear motions of a linear motor by connecting the piston directly to a rotor of the motor. Since the linear type reciprocating compressor has no crankshaft for converting rotary motions into rectilinear motions, frictional loss is small. Further, the linear type reciprocating compressor has compression efficiency higher than that of a general compressor.
A refrigerator having a compressor generally includes a compressor controller for controlling operations of the compressor and a refrigerator controller for controlling operations of the refrigerator. In this case, the compressor controller detects current and voltage flowing in the compressor and controls a stroke, speed, etc., using the detected current and voltage. The refrigerator controller controls the power of the compressor by outputting a control signal for turning on or off the compressor controller according to a refrigerator load, e.g., a temperature in the refrigerator, and accordingly, the refrigerator is driven.
In a refrigerator having a linear compressor or BLDC reciprocating compressor, the compressor receives commercial power, and is driven through a driver having a power device such as an inverter. The compressor performs operations of on/off, cooling capacity variation, speed control, frequency control, stroke control, etc. according to a command requested by the refrigerator. Accordingly, the refrigerator maintains the temperature in the refrigerator to an appropriate level through the operation of the compressor.
However, in a compressor control device and method, and a refrigerator having the same according to a conventional art, a compressor is always operated through a power conversion device having an inverter, and therefore, loss caused by the driving of the compressor occurs.